Centrifugal fan with a multistage impeller

ABSTRACT

A centrifugal fan with a multistage impeller includes a hub and a multistage impeller having at least two stages of blade assemblies. The hub has a top section and a circumferential section extending from the top section. At least one extension section outward extends from the circumferential section. The multistage impeller is connected with one end of the extension section. The multistage impeller includes a first-stage blade assembly and a second-stage blade assembly. The second-stage blade assembly has a diameter larger than that of the first-stage blade assembly. The centrifugal fan can be installed in an application environment with limited space without being interfered with by peripheral parts. Also, the centrifugal fan is able to provide an optimal flow and wind pressure at the same rotational speed to lower the load on the motor and reduce the noise.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a centrifugal fan with a multistage impeller, and more particularly to a centrifugal fan having at least two stages of blade assemblies. The centrifugal fan can be installed in an application environment with limited space without being interfered with by peripheral parts. Also, the centrifugal fan is able to provide an optimal flow and wind pressure at the same rotational speed to lower the load on the motor and reduce the noise.

2. Description of the Related Art

Recently, thanks to rapid advance of electronic industries, the performances of various electronic components have been more and more promoted. To increase the operation speed of the electronic component, the number of the chips in the electronic component is continuously increased and the processing speed of the chip sets in the electronic component is continuously enhanced. Under such circumstance, the chips will generate high heat when working. The heat generated by the chips must be quickly dissipated. Otherwise, the temperature of the electronic component will rise very quickly to cause deterioration of the performances of the electronic component, slowdown of the operation speed of the electronic component, crash or even burnout of the electronic component. Therefore, it has become an important issue how to quickly dissipate the heat generated by the chips. In general, a cooling fan is used as a heat dissipation device for dissipating the heat.

Various fans are widely used in different fields for ventilation, exhaustion, air exchange, temperature control, etc. According to the function and property, the fans available in the current market can be classified into three major types, that is, centrifugal fans, diagonal flow fans and axial flow fans. These fans are applied to different sites to meet different requirements in working.

FIG. 1 is a perspective view of a conventional centrifugal fan. The centrifugal fan 1 includes a hub 11 and a blade assembly 12. The hub 11 has a top section 111 and a circumferential section 112 extending from a periphery of the top section 111. At least one extension section 113 outward extends from the circumferential section 112 in a direction away from the top section 111. The blade assembly 12 is disposed on the extension section 113. The blade assembly 12 includes multiple blades classified into upper blades 121 and lower blades 122. The upper and lower blades 121, 122 are horizontally connected with each other by means of an annular plate 13. The upper and lower blades 121, 122 via the annular plate 13 are arranged around the hub 11. The upper and lower blades 121, 122 have equal diameters so that the centrifugal fan 1 has a unified diameter.

As aforesaid, the centrifugal fan 1 has a unified diameter. Therefore, when installing the centrifugal fan 1, it often takes place that it is impossible to install or use the centrifugal fan 1 due to limitation of space or interference of peripheral parts. Under such circumstance, it must be compromised to install and use a smaller centrifugal fan with a unified diameter. The smaller centrifugal fan often fails to provide a flow meeting the designed flow value. In this case, it is necessary to increase the rotational speed of the smaller centrifugal fan. As a result, the centrifugal fan will make greater noise and the load on the motor will be increased.

According to the above, the conventional centrifugal fan has the following shortcomings:

-   1. The installation space of the conventional centrifugal fan is     limited. -   2. The installation of the conventional centrifugal fan is subject     to interference of peripheral parts. -   3. The conventional centrifugal fan can hardly provide a flow     meeting the designed flow value. -   4. The conventional centrifugal fan will make greater noise and the     load on the motor will be increased.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a centrifugal fan with a multistage impeller having at least two stages of blade assemblies. The multistage impeller has non-unified diameters. Therefore, the centrifugal fan can be installed in an application environment with limited space without being interfered with by peripheral parts.

A further object of the present invention is to provide the above centrifugal fan with the multistage impeller. The centrifugal fan is able to provide an optimal flow and wind pressure at the same rotational speed.

A still further object of the present invention is to provide the above centrifugal fan with the multistage impeller. The centrifugal fan is operable with lower load on the motor and reduced noise.

To achieve the above and other objects, the centrifugal fan with the multistage impeller of the present invention includes a hub and a multistage impeller having at least two stages of blade assemblies. The hub has a top section and a circumferential section extending from a periphery of the top section. At least one extension section outward extends from the circumferential section in a direction away from the top section. The multistage impeller includes a first-stage blade assembly and a second-stage blade assembly. The first-stage blade assembly is connected with one end of the extension section, which end is distal from the circumferential section. The second-stage blade assembly is positioned on one side of the first-stage blade assembly. Each of the first-stage blade assembly and the second-stage blade assembly includes multiple blades annularly arranged around the hub. A first connection section is connected between each two adjacent blades of the first-stage blade assembly. The blades of the first-stage blade assembly are annularly connected with each other by means of the first connection sections. A second connection section is connected between each two adjacent blades of the second-stage blade assembly. The blades of the second-stage blade assembly are annularly connected with each other by means of the second connection sections. The second-stage blade assembly has a diameter larger than that of the first-stage blade assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a conventional centrifugal fan;

FIG. 2 is a perspective view of a first embodiment of the present invention;

FIG. 3 is a side view of the first embodiment of the present invention;

FIG. 4 is a side view according to FIG. 3, showing that the centrifugal fan of the present invention is accommodated in a multistage fan housing;

FIG. 5 is a perspective view of a second embodiment of the present invention;

FIG. 6 is a side view of the second embodiment of the present invention;

FIG. 7 is a perspective view of a third embodiment of the present invention; and

FIG. 8 is a side view of the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 2 and 3. According to a first preferred embodiment, the centrifugal fan 2 with the multistage impeller of the present invention includes a hub 3 and a multistage impeller 4 having at least two stages of blade assemblies. The hub 3 has a top section 31 and a circumferential section 32 extending from a periphery of the top section 31. At least one extension section 33 outward extends from the circumferential section 32 in a direction away from the top section 31. A first end of the extension section 33 is connected with the circumferential section 32. The multistage impeller 4 includes a first-stage blade assembly 41 and a second-stage blade assembly 42. The first-stage blade assembly 41 is arranged at a second end of the extension section 33 opposite to the first end. The first-stage blade assembly 41 includes multiple blades arranged around the hub 3. A first connection section 411 is connected between each two adjacent blades of the first-stage blade assembly 41. The blades are annularly connected with each other by means of the first connection sections 411 to form the first-stage blade assembly 41 in an annular form. The second-stage blade assembly 42 is positioned on upper side of the first-stage blade assembly 41. The second-stage blade assembly 42 includes multiple blades arranged around the hub 3. A second connection section 421 is connected between each two adjacent blades of the second-stage blade assembly 42. The blades are annularly connected with each other by means of the second connection sections 421 to form the second-stage blade assembly 42 in an annular form. A first-stage annular plate 412 is positioned between the first-stage blade assembly 41 and second-stage blade assembly 42. The second-stage blade assembly 42 is arranged on the upper side of the first-stage blade assembly 41 via the first-stage annular plate 412.

The extension section 33 is connected to the first connection section 411 of the first-stage blade assembly 41. The multiple blades of the first-stage blade assembly 41 are arranged at equal intervals and perpendicularly extend from the first connection sections 411. The blades are annularly connected with each other via the first connection sections 411. The first-stage annular plate 412 is disposed on the upper side of the first-stage blade assembly 41. The first-stage annular plate 412 extends along an outer circumference of the upper side of the first-stage blade assembly 41. The second-stage blade assembly 42 is arranged on the other side of the first-stage annular plate 412. The first-stage annular plate 412 extends along an inner circumference of lower side of the second-stage blade assembly 42. Accordingly, the second-stage blade assembly 42 has a diameter larger than that of the first-stage blade assembly 41. Therefore, the combination of the first-stage blade assembly 41 and the second-stage blade assembly 42 has non-unified diameters.

Please refer to FIGS. 2, 3 and 4. The centrifugal fan 2 is composed of the hub 3, the first-stage blade assembly 41 and the second-stage blade assembly 41. When installed, the centrifugal fan 2 is mounted in a multistage fan housing 5. The multistage fan housing 5 includes a first-stage case 51 adapted to the first-stage blade assembly 41 and a second-stage case 52 adapted to the second-stage blade assembly 42. When assembling the centrifugal fan 2 with the multistage fan housing 5, the second-stage blade assembly 42 is disposed in the second-stage case 52, while the first-stage blade assembly 41 is disposed in the first-stage case 51. Accordingly, the centrifugal fan 2 can be completely accommodated in the multistage fan housing 5. In this case, the centrifugal fan 2 can be installed in an application environment with limited space without being interfered with by peripheral parts. Also, the centrifugal fan 2 is able to provide an optimal flow and wind pressure at the same rotational speed to lower the load on the motor and reduce the noise.

Please refer to FIGS. 5 and 6, which show a second embodiment of the present invention. The second embodiment is substantially identical to the first embodiment in structure and connection relationship between the components and thus will not be repeatedly described hereinafter. The second embodiment is only different from the first embodiment in that the multistage impeller 4 of the centrifugal fan 2 is a three-stage impeller further including a third-stage blade assembly 43. The second-stage blade assembly 42 is arranged on the upper side of the first-stage blade assembly 41 via the first-stage annular plate 412. A second-stage annular plate 422 is positioned on the other side of the second-stage blade assembly 42, which side is distal from the first-stage blade assembly 41. The third-stage blade assembly 43 is arranged on the other side of the second-stage annular plate 422. The third-stage blade assembly 43 includes multiple blades arranged around the hub 3. A third connection section 431 is connected between each two adjacent blades of the third-stage blade assembly 43. The blades are annularly connected with each other by means of the third connection sections 431 to form the third-stage blade assembly 43 in an annular form. The second-stage annular plate 422 extends along an outer circumference of the upper side of the second-stage blade assembly 42 and along an inner circumference of lower side of the third-stage blade assembly 43. Accordingly, the third-stage blade assembly 43 has a diameter larger than that of the second-stage blade assembly 42. Therefore, the combination of the first-stage blade assembly 41, the second-stage blade assembly 42 and the third-stage blade assembly 43 has non-unified diameters. According to the above arrangement, more blade assemblies and annular plates with different diameters can be added to the multistage impeller 4 in accordance with different application environments to form a multistage impeller with non-unified diameters.

Please refer to FIGS. 7 and 8, which show a third embodiment of the present invention. In the third embodiment, the first-stage blade assembly 41 is arranged at the second end of the extension section 33 extending from the hub 3. The first-stage annular plate 412 is positioned between the first-stage blade assembly 41 and the second-stage blade assembly 42. The first-stage annular plate 412 extends along the outer circumference of the lower side of the first-stage blade assembly 41. The second-stage blade assembly 42 is arranged on the other side of the first-stage annular plate 412. The first-stage annular plate 412 extends along an inner circumference of the upper side of the second-stage blade assembly 42. Accordingly, the second-stage blade assembly 42 has a diameter larger than that of the first-stage blade assembly 41. Therefore, the combination of the first-stage blade assembly 41 and the second-stage blade assembly 42 has non-unified diameters. In this case, the centrifugal fan 2 of the present invention can be installed in an application environment with limited space without being interfered with by peripheral parts. Also, the centrifugal fan 2 is able to provide an optimal flow and wind pressure at the same rotational speed to lower the load on the motor and reduce the noise.

According to the above arrangement, the centrifugal fan with the multistage impeller of the present invention has the following advantages:

-   1. The centrifugal fan with the multistage impeller of the present     invention can be installed in an application environment with     limited space. -   2. The centrifugal fan with the multistage impeller of the present     invention can be installed in an application environment without     being interfered with by peripheral parts. -   3. The centrifugal fan with the multistage impeller of the present     invention is able to provide an optimal flow and wind pressure at     the same rotational speed. -   4. The centrifugal fan with the multistage impeller of the present     invention is operable with lower load on the motor and reduced     noise.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. It is understood that many changes and modifications of the above embodiments can be made without departing from the spirit of the present invention. The scope of the present invention is limited only by the appended claims. 

1. A centrifugal fan with a multistage impeller, the centrifugal fan comprising: a hub having a top section and a circumferential section extending from the top section, at least one extension section outward extending from the circumferential section in a direction away from the top section; and a multistage impeller having at least two stages of blade assemblies, the multistage impeller including a first-stage blade assembly and a second-stage blade assembly, each of the first-stage blade assembly and the second-stage blade assembly including multiple blades annularly arranged around the hub, the first-stage blade assembly being connected with one end of the extension section, the second-stage blade assembly being positioned on one side of the first-stage blade assembly, the second-stage blade assembly having a diameter larger than that of the first-stage blade assembly.
 2. The centrifugal fan with the multistage impeller as claimed in claim 1, wherein the centrifugal fan is mounted in a multistage fan housing.
 3. The centrifugal fan with the multistage impeller as claimed in claim 1, wherein a first connection section is connected between each two adjacent
 4. The centrifugal fan with the multistage impeller as claimed in claim 1, wherein a second connection section is connected between each two adjacent blades of the second-stage blade assembly, the blades of the second-stage blade assembly being annularly connected with each other by means of the second connection sections to form the second-stage blade assembly in an annular form.
 5. The centrifugal fan with the multistage impeller as claimed in claim 1, wherein a first-stage annular plate is positioned between the first-stage blade assembly and the second-stage blade assembly, the second-stage blade assembly being arranged on one side of the first-stage blade assembly via the first-stage annular plate.
 6. The centrifugal fan with the multistage impeller as claimed in claim 5, wherein a second-stage annular plate is positioned on the other side of the second-stage blade assembly, which side is distal from the first-stage blade assembly, a third-stage blade assembly being arranged on the other side of the second-stage annular plate.
 7. The centrifugal fan with the multistage impeller as claimed in claim 6, wherein the second-stage annular plate has a diameter larger than that of the first-stage annular plate.
 8. The centrifugal fan with the multistage impeller as claimed in claim 6, wherein the third-stage blade assembly includes multiple blades annularly arranged around the hub, a third connection section being connected between each two adjacent blades of the third-stage blade assembly, the blades of the third-stage blade assembly being annularly connected with each other by means of the third connection sections to form the third-stage blade assembly in an annular form.
 9. The centrifugal fan with the multistage impeller as claimed in claim 8, wherein the third-stage blade assembly has a diameter larger than that of the second-stage blade assembly. 